1. Field of the Invention
The present invention relates generally to a process for fabricating glass tooling such as molds with featured surfaces.
2. Description of the Prior Art
A typical process for making featured-surface tooling is shown in FIGS. 1a to 1g. A polished glass blank 22, FIG. 1a, is coated with a layer of photoresist 24, FIG. 1b. A latent image is written onto the photoresist layer by means of modulated laser light focused by an optical system 26 (FIG. 1c) so that it is registered in the form of a pattern of voids in the developed photoresist layer (FIG. 1d). After application of a release layer, a thin nickel layer 28 (FIG. 1e) is electrochemically deposited onto the patterned side of the glass blank and is then removed to form a single metal negative copy of the vulnerable master which is destroyed in the process, this copy being referred to in the industry as the "father." Electrochemical copying of the father produces a limited number (six or so) of "mother" copies 30 (FIG. 1f) before the father has deteriorated to the point that the resolution of additional mothers would be unsatisfactory. The mothers are positive copies of the master, and are themselves copied a limited number of times to produce negative "son" copies 32, as shown in FIG. 1g. The sons are used as tooling having a featured surface. This "family" process is necessary so that many production tools may be made from a single glass master mold. However, each generation of the family, and each succeeding member of the same generation, suffers increasing resolution degradation.